The prior art discloses a number of arrangements for displaying directory information and the like. Such systems are generally characterized by their complexity and relatively high expense. Also, prior art systems often are so constructed as to make the job of changing information displayed a difficult, time-consuming, awkward and expensive matter.
A common form of directory display case is that incorporating metal face panels having windows to support plastic holders which in turn hold photo-negatives bearing the indicia to be displayed. Changing the photo-negatives requires removal of the entire holder to replace the photo-negative, either individually through a side opening in the directory display case or in conjunction with the other holders as a unit.
Not only do prior art display case arrangements make the replacement of information strips a difficult matter, prior art directories and the like which incorporate the use of removable strips in association with a lighted back panel often present an unsightly appearance because of the light leak problems which exist about the strips. That is, the observer is not only presented with the lighted strip itself but a display of light located at the strip edges, either wholly or partially about the periphery of the strip. This problem becomes even more aggravated because of the tendency of strip material to warp when heated, as for example, by electric lamps providing the source of light for the directory.
Yet another problem inherent in prior art approaches is the fact that such systems can only accommodate a single strip size.
Representative of prior art approaches are those disclosed in the following patents: U.S. Pat. No. 3,905,139, issued Sep. 16, 1975; U.S. Pat. No. 3,824,722, issued Jul. 23, 1974; U.S. Pat. No. 4,654,101, issued Mar. 31, 1987; and United Kingdom Patent Application Publication No. 2,117,547, published Oct. 12, 1983.